/*
 * Copyright 2010 Brian Watkins
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package bw.refresh;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import bw.util.*;
import bw.os.ObjectStore;

import com.google.appengine.api.labs.taskqueue.Queue;
import com.google.appengine.api.labs.taskqueue.QueueFactory;
import static com.google.appengine.api.labs.taskqueue.TaskOptions.Builder.*;
import static com.google.appengine.api.labs.taskqueue.TaskOptions.Method;

public class RefresherServlet extends HttpServlet
{
    public static final String TASK_ID = "taskId";
    //for appengine cron use X-AppEngine-Cron
    public static final String REFRESH_HEADER = "X-WD-REFRESH";

    //check for refresh after a minute
    private int _refreshMins = 1;
    private long _lastRefreshed = 0L;

    public void doGet ( HttpServletRequest req, HttpServletResponse res )
        throws ServletException, IOException
    {
        if ( "true".equals( req.getHeader( REFRESH_HEADER ) ) )
        {
            Log.getInstance().write( "RefresherServlet: Doing a refresh!" );
            
            RefresherPool.getInstance().performAction();

            res.setContentType( "text/xml" );
        }
        else
        {
            long refreshMillis = _refreshMins * 60 * 1000L;
            if ( ( System.currentTimeMillis() - _lastRefreshed ) > refreshMillis )
            {
                Queue queue = QueueFactory.getDefaultQueue();
                queue.add( url( "/refresh" ).header( RefresherServlet.REFRESH_HEADER, 
                                                     "true" ).method( Method.GET ) );
                _lastRefreshed = System.currentTimeMillis();
            }
        }

        PrintWriter out = res.getWriter();
        out.println( "OK" );
        out.close();
    }

    public void doPost ( HttpServletRequest req, HttpServletResponse res )
        throws ServletException, IOException
    {
        String taskId = req.getParameter( TASK_ID );
        if ( taskId != null && taskId.length() > 0 )
        {
            Log.getInstance().write( "Performing task: " + taskId );
            
            try
            {
                Refreshable r = (Refreshable) ObjectStore.getInstance().get( taskId );
                r.refresh();
            }
            catch ( Exception ex )
            {
                Log.getInstance().write( "Problem refreshing task: " + taskId, ex );
            }
        }
    }
}